Method and apparatus for forming sheet metal stock



Feb. 9, 1960 E. F. HUFGARD ET AL 2,924,262

METHOD AND APPARATUS FOR FORMING SHEET METAL STOCK Filed Feb. 12, 1958 3 Sheets-Sheet l INVENTORS. All/605T YZ/EKA, 12., EDW/N J. HUFGAE'D, JOJEPH M, ANTOCHOW,

Q2422. 4 TTOPNEY Feb. 9, 1960 E. F- HUFGARD ETAL 2,924,262

METHOD AND APPARATUS FDR FORMING SHEET METAL STOCK s She ets-Sheet 2 Fiid Feb. 12. 1958 H MAIAC N T 0 ,R NKFT 0 EEU 7 w: 7 J 4 mm 6 4% 00M AE Y. 5

Feb. 9, 1960 E. F. HUFGARD ETAL 2,924,262

METHOD AND APPARATUS FOR FORMING SHEET METAL STOCK Filed Feb. 12, 1958 5 Sheets-Sheet 5 INVENTORJ. AUGUST YUEKA, .72., t'DWl/V J. HUFGARD,

JOSEPH M. AN7Z7CHOVV.

United States Patent METHOD AND APPARATUS FOR FORMING SHEET METAL STOCK Edwin F. Hufgard, South Euclid, Joseph M. Antochow, Maple Heights, and August Yurka, Jr., Cleveland Heights, Ohio, assignors to The Cyril Bath Company, Solon, Ohio, a corporation of Ohio Application February 12, 1958, Serial No. 714,907

3 Claims. (Cl. 153-46) This invention relates to a method and apparatus for forming sheet metal stock in dies, and particularly to an improvement in methods and apparatus whereby a length of stock is wrapped about a curved face of a male forming die progressively from one portion of the stock, endwise of the stock, to another portion of the stock.

An important feature of the present invention resides in the fact that, during wrapping, tension is applied to the stock, endwise of the stock, at only a limited portion of itswidth so as to stretch that portion, and the stock is maintained substantially free from endwise tension at another portion of its width.

More specifically, the invention relates to the progressive endwise bending, into a form curved about an axis extending transversely of its length, of a sheet of metal which has an inturned compression flange along one'of its margins--has an out-turned tension flange at a location spaced laterally of the sheet from the first flangefor example, adjacent its other lateral margin, and, at th outer edge of the tension flange, has an offset flange which may be parallel to the main body of the sheet and which, at its laterally outermost margin, is connected to a second out-turned tension flange.

In forming sheet metal stock with flanges of this general character, the male die is provided with a suitable configuration for fitting the cross section of the flanged sheet, the sheet having been so configured in cross section while flat and prior to forming.

In the illustrative example herein disclosed, the male die, therefore, has at one lateral limit a compression flange forming face and, spaced therefrom laterally of the die, as required for fitting the cross section of the sheet, a tension flange forming face which extends outwardly from the plane of the sheet. Also, the male die has an offset flange forming face portion which is disposed along the outer edge of the tension flange forming face so as to engage the inner face of the offset flange of the sheet. Finally, the die has a second tension flange forming face which extends radially outwardly from the laterally outermost margin of the offset flange forming face.

1 pression and tension flanges of the sheet, which extend radially of the curvilinear portion of the male die, are

well confined against the male die faces as they are bent around the curvilinear portions.

Thus there is presented the problem of maintaining the sheet of stock in proper unskewed position in the dies while forming the sheet about a die progressively endwise of the sheet in a manner which necessitates that the sheet be stretched endwise of the sheet different amounts at different portions of its width, and that it left unconstrained and free from endwise stretching at other portions of its width.

In the illustrative example, the forming is done by means of a wing die which has a face complementary to the male die and which is adapted to be rolled about the curvilinear end face of the male die to wrap the stock thereon. With such an unsymmetrical sheet cross section as that described, tension is applied by a hold-down device which holds the tension flanges and offset flange in fixed position relative to the wing die during the forming operation, and, accordingly, a specific object of the present invention is to provide a hold-down device for this purpose.

In structures of this character, since the wing die rocks or rolls about the rounded or curvilinear portion at the end of the male die, the path of any point on thewing die is not a circular path about the axis of the rounded portion of the male die. Consequently, any hold-down device not only must be arranged so that it can remain firmly clamped in fixed position relative to the wing die 3 during the forming operation, can be readily removed These faces extend endwise of the die around the end flanges, and the offset flange each must be subjected to different stresses and strains during the forming thereof about the curvilinear portion of the die. The comp-ression flange necessarily must be compressed because of its relatively shorter radius in the formed piece than the.

other portions of the piece.- The tension flanges and the ofiset flange necessarily must be subject to tension because as the wing die is lowered, and can be readily replaced in clamping position, but also must be arranged so that it can be positioned properly in respect to the wing die for holding the sheet at the required portion and can move with the wing die in a path other than a circular path about the axis of the curvilinear part of the .male die. The manner in which the problem is solved and the advantages resulting therefrom will become readily apparent from the following description wherein reference is made to the drawings, in which Fig. 1 is a front elevation, partly in section, of a sequence bending press embodying the principles of the present invention;

Fig. 2 is a side elevation of the structure illustrated in Fig. 1, part thereof being shown in section;

Fig. 3 is an enlarged fragmentary side elevation of the structure illustrated in Figs. 1 and 2, showing the holddown or clamping device, part thereof being shown in section for clearness in illustration; and

Figs. 4 and 5 are an enlarged fragmentary front elevation and a top plan view, respectively, of the structure illustrated in Fig. 3.

For the purposes of illustration, the present invention is shown installed for use in a press of the general character disclosed in the Bath and Ebert United States Patent No. 2,642,114, issued June 16, 1953, wherein the operatingparts of the press, the power mechanism, and the hydraulic circuits are all fully disclosed, its use in connection with other structures being readily apparent from the illustrative example.

Since the present invention relates to the manner of tensioning a sheet of stock across part only of its width while wrap forming it progressively endwise around a part of the curved face of the male die, and the means for causing the proper tensioning, the description of the it is necessary to stretch them to conform to greater radii than the remainder of the sheet. The different stresses and strains imposed on the sheet because of the different lengths of radii cause the sheet to skew in the dies during forming, thus destroying the sheet andfailing to produce a proper formation. This is true even though the com press and the operation thereof will be described only briefly herein.

The press comprises a frame 1 having an upwardly facing horizontal die bed 2 on which is mounted a 'female forming die 3.

Mounted in fixed position on one end of the frame is Patented. Feb. 9,1960.

"r"? (Fr-r m an upright, rigid guide column 4 which strait, su

porting a ram 5. The ram carries a forming male die,

6 which is complementary to the die 3. I

The ram is connected at the end adjacentthe column 4 to a suitable piston and cylinderassemblage 10 which is adapted to lift and lower the ram on its operating stroke. At the opposite end of the ram is a'piston and, cylinder assemblage 11 which is detachably connectedtd the cooperating die 3 on the bed 2 for a portion-of its length, and is to be formed around the curvilinear end faces of the die 6. For this purpose, suitablewing dies 15 are provided, one for each end margin of the die 6; Since the ends of the die 6 and their associated wing dies are the same, one only will be described in detail;

For mounting the wing die 15, a suitable wing die carriage 16 is provided and extends lengthwise of the ram for substantially the'full length of the Wing dies. The carriage is provided at its ends with arms 16a by which it is connected to' suitable pivots 17. Normally;

of theassociated male die 6. The wing die is then swung downwardly by reversal of the assemblage 25, after which the latches are released and the ram raised so as to remove the piece of formed stock.

The manner of operating the parts described is fully. disclosed in the above enti-tled patent.

The structure thus far described is recognized as, old

.7 in the" above" patent and, of itself, does not form'the present invention.

As best illustrated in Fig. 2, it frequentlyhappens that lengths of stock are to be formed which. do not readily.

retain their position in the dies due to the different stresses required at diflferent portions.- For example, as illustrated in Fig.2, there is shown a length ,of stock which in cross section has an inturned compression flange A along one. margin, an outturned tension flange B near the other margin, the flange B being connected at its outer margin to an, outwardly offset, flange C which is parallel to the.

main'body of the material, and the. flange C, in"turn,..

the carriage depends from the pivotal connection :below the level of the bed and lies alongside one side of the frame, as illustrated, and is adapted tobeswung-upwargly about the pivotal axis on the wing die forming stro e. V

Mounted within thecarriage and substantially coexteh sive in length therewith is a roller18. The ends of the rollers are carried in suitable bearings which are mounted in suitable slideways in the carriage 16 for sliding movement toward and away from the pivotal axis of the carriage, whereby the roller is movable transversely of its axis in the carriage toward and away from the pivotal axis. The rollers are urged toward the axis of the pivots 17 by springs 19, all as more fully described in'the above identified patent. i

Resting in the carriage 16 is a rocker plate 20 which is normally horizontal and faces upwardly and the roller 18 rolls along its under surface.

being connected to another outwardly extendingoutturned tension flange D. The die 6 is formed to fit this cross section and,the companion wing die is correspondingly formed However, in structuresof character it is; apparent that in wrapping the stock around the curvilinear face 'at themargin of the die 6, that there is a con-.

siderable amount of stretching required to form the flanges- B,'C, andD, while the flange A must be compressed.

i If an attempt is, made to form this in the usual manner, it will be found that the stock tends to creeplaterally, and skew in the diesiso that it does not form the proper. shape. Further, it.is necessary that a portion, of the width of the stock correspondingly to the portion which is formed in the flanges B, C and D must be placedi under tensionmduring' the forming operation, and this;

tension must be sufficient to stretch the stock during the forming operation. The compression die flange A can. be formed readily enough by being gripped between cooperating faces, such as the compression flange face on' the die. 6 and the complementary compressionflange face 'on'tlie 'wingdie 15. On the otherhand, even thoughthe die 6 and the wing die, 15 have cooperating tension flanging faces and offset flanging faces for forming the flanges B, C and D, nevertheless these cannot be confined and The plate 20 is pro vided with a key 21 which engages a peripheral groove 21a in the roller to prevent movement of the plate .20

endwise of the roller. The 'plate'20 is provided. with arms 22, the upper edges of which are in the form or racks 23. The racks, in turn, engage suitablegear-Jsegments 24 secured to the frame and coaxial with the pivots 17. Thus the rocker plate is guided as it is rocked from the lowered position upwardly, along and tangent to, therounded end face of the die 6. Suitable power means may be used to operatethe carriages 16. In the form illustrated, this means is a piston and cylinder assemblage 25 which is connected at one end to the frame and at the other end to the carriage 16. Upon swinging of the carriage upwardly about the axis of its pivots, the rocker plate and the wing die carried thereby are rolled from their horizontal position upwardly and around the rounded end face of the die 6 and form and lay the stock to be formed around such end face.

Thus, in order to form a piece of stock into the top,

and sides of a cabinet with flanges thereon, the stock,

with its cross sectional contour preformed, is laid in posi tion onone of a female die 3, the ram is moved downwardly to clamp the piece between the die 3 and the die 6, and, when the stock is so held at this position, the carriage is swung upwardly by the piston and cylinder as semblage 25, thus rocking the wing die 15 upwardly, and forming the. stock about the adjacent rounded fend face formed properly unlessthey are placed under tension.

At the same time, it is desirable'that the remainder of the width of the stock remain free from-any tensioning force and rnerelywrap aroundthe curvilinear face along the margin of the die 6.

In' order to stretchthe stoclthlongthe portion of its.

width corresponding to the flanges B, .C, D, while leaving the remainder of thestock unstretched, a suitable clamping device is provided by which the. stock is. clamped firmly in fixed position relative to the wing die 15 near the end of the stock at the portion of the cross section corresponding in widtli to the flanges. B,. C, and D. Thus,

whenthe "wing die is rocked or rolled about the curvi linear face of the die 6,the portions B, C and D are thrown into tension. adequate to impart the necessary stretch so that each will conform to the die 6 at those portions of the die 6 having diflferent radli." At first 1t might appear thattoo much difficulty would not be encountered in'clarnping ofthe stock for this purpose, but

difliculties are introduced because of the factthat the wing die. does not swing about a fixed pivot but, on the contrary, rolls about a fixed'pivot so that all P011118 thereon move in non-circular curvilinear paths.

To overcome. these difiiculties, the structurenow to: be describedisprovided. Mounted on the rocking plate I 20 adjacent the edge of the die 15 which has the tension flanging faces and the ofiset flanging face, there is provided. a suitable complementary to C and D. The plate. tion and the stock is resting freely on the wing die 15 a gmented and is engaged by thedie 6. The shoe gripping shoe,30.having gripping faces the faces which, form the flanges 3,;

20 is in a lower horizontal posi is-placed inthe position illustrated "in Fig. 4' and clamped in that position so as to hold that portion of the stock in fixed position relative'to the wing die. Forclamping the shoe 30in this position thereisprovided on the plate 20 a reversible hydraulic piston and cylinder assemblage including a suitable cylinder 31 and reciprocal piston 32. The piston 32 has spring operated return rods 33. At its outer end, it engages a clamp-head 34'which'is arranged so'that, when the piston andcylinder assemblage is extended, the head -34 engages the outer face of the shoe 30. and forces it toward the die,'so that itlfirmly clamps the faces B and ,C of t he stock against the die flange forming faces. The hydraulic fluid is introduced to the cylinder so as to create this clamping pressure prior to the operation of the wing dies and while the shoe is held pressed down by the positioning means, later to be described. The head 34 is operable to maintain the hold clamping pressure during the forming operation, the clamp being loosened and released after the piece has been formed.

In order to position the shoe into its operating position for clamping the piece of stock, suitable power means are provided. The power means are in the form of a piston and cylinder assemblage 36, the cylinder of which is pivotally connected at one end, as indicated at 37, to the ram 5, and the piston rod 38 of which is pivotally connected to the shoe 30, as indicated at 39.

The shoe 30 and the ram 5 are pivotally connected together so that the shoe 30 can be rocked relative to the ram 5 into the clamping position. However, it is to be noted that as the plate 20 is rocked upwardly about the curvilinear face of the die 6, with the shoe 30 held in fixed position on the wing die 15, that the pivotal connection between the shoe 30 and the ram cannot remain in a fixed position relative to both the shoe 30 and the ram 5. This is because the path of the shoe 30 is not a circular path concentric and of varying radius. An indication of this path is illustrated in Fig. 3 wherein the forming face portion of the shoe 30 is indicated by various lines in different positions, these lines being designated as L through R, respectively. Accordingly, therefore, there must be a migration of the pivotal axis relative to the shoe or to the ram 5 or both in order that the operating faces of the shoe remain in fixed position on the wing die. Such a migratory pivotal axis may be provided by providing a fixed pivot on the shoe which engages an elongated slot on the ram, or, as preferred and illustrated, by a fixed pivot 40 on the ram which operates in an elongated slot 42 in the shoe. Thus the shoe is mounted for pivotal movement about a migratory pivotal axis during the forming operation and during its initial provided by the piston and cylinder assemblage 36 must be overcome by the force of the piston and cylinder assemblage 25 which lifts the plate 20 during the forming operation. Further, due to the angularity of the line of thrust, the assemblage 36 would tend to apply to the shoe 30 a force which would urge the shoe to slip or move endwise of the wing die 15. Positive clamping pressure afforded by the clamp 32 is preferred.

As mentioned, a similar arrangement is provided at each side of the die 6, assuming that the part to be formed is to have the rounded portions near each end of the male die.

In operation, therefore, the piece of stock is placed on the die 3 with the wing die 15 in horizontal position. The stock has been preformed in cross section to provide the flanges A through D. While thus accommodated 'with its flanges fitting the corresponding faces of the dies 3 and 15, the die6 is lowerediand firmlyiclampsthe' piece of stock between the dies 6 and'3. Next, the shoe-30' is lowered and pressed into position by the assemblage 36 and while so held, clamped by means of the clamping head 34operated by the piston 32. Thereupon, the fluidpressure may be relieved inthe'head end of the assentblage 36 so that the shoe is held only by the clamp.

Thereuponf the wing die 15 is operated to roll upwardly andform the piece about the die 6 while the shoe 30 is held in firm clamping relation. As the wing die 15 is rolled upwardly, the axis of the pivot 40 migrates relativeto the shoe 30 toipermit accommodation of the shoe to thenon-circular eccentric path of the wing die and shoe while. maintaining its fixed position relative to the wing die 15. At the end of the forming stroke, the clamping head 34 is released and fluid pressure is admitted to the rod end of the assemblage 36 to withdraw the clamping shoe whereupon the wing die can be withdrawn from the piece and lowered, the die 6 raised, and the piece can be removed.

After the piece is removed, the shoe 30 is held by the assemblage 36 out of position, awaiting the placing of another piece within the dies in proper relation for formmg.

In this manner, a length of stock is progressively formed lengthwise from one portion along its length to another portion along its length about a die having a forming face curved about an axis extending transversely of the stock, the stock being laid on the die face progressively endwise of the stock while maintaining the stock, for one portion of its width, under suflicient tension to stretch it while for the remainder of its width it is unconstrained and free from the application of the tensioning force. As a result, pieces can be formed without skewing in the dies and so that they conform to the proper shape.

Having thus described our invention, we claim:

1. In a bending apparatus including a male die memher having two angularly disposed faces and a rounded face curved about an axis extending transversely of the male die member and joining, and tangential to, the angularly disposed face, and said male die member having at one lateral limit of the rounded face a transverse flange face substantially concentric with said rounded face and of greater radius than said rounded face, said flange face being coextensive endwise of the male die member with the rounded face, a wing die having a face adapted to roll about said rounded face and having a transverse flange face adapted to roll about the flange face of the male die member, during said rolling action of the wing die, a wing die support for supporting the wing die and for rolling it about the rounded face of the male die member, a holding shoe member having a surface complementary to the flange face of the wing die and cooperable with the flange face of the wing die to engage and hold a flange portion of a length of stock fitting the flange face of the wing die in fixed position relative to the flange face of the wing die, positioning power means including a power operated extensible compression device pivotally connected at one end to the shoe member and pivotally connected at the other end for swinging about an axis in fixed relation to the male die member, and operable to move the shoe member 'into, and temporarily hold it in, said cooperating position relative to the wing die, clamping power means carried by the support and operable to engage the shoe member and clamp it firmly in cooperative relation to, and in fixed position relative to, the wing die during said rolling of the wing die, for holding the engaged flange portion of the stock in fixed position relative to the wing die, and to release the shoe forming operation, and being operable to retract further and remove the shoe from the stock when the power means releases the shoe at the end of the forming operation.

2. The 1 structure according ioxclaini 1 h wherein lithe: shoe member is; harried" by a member, migratory pivotme'ans connebtedtogetherfdn concurrent; rotation? relative to each other and relative'rmovement transversely 1 of-"thein pivotal axes conneoting the shoe member relative to the ram member for pivotal movement :.of the shoe member relative to'the 'male die member in a non-.. circular path as the wing die is operated onits: forming strokenwithlthe shoe'member heldin fixed po'sitionirelative to the wing .die. I

3. Thestructureaccordingto claim leharacterizeiin that the clamping power means includes a. clamp head mounted for movement with the. wing die-as the wing die is rolled on its operating stroke and for movement relati'veeto the Ming die" transversely Iof :thelwing die; iam'h saidi' clamp head normally vi positioned laterally or athe iwingj die? foni receiving amt-clamping; a I portion; oil thev :shoeE- membenbetween rche rclampheadfwand the wing die: 1:":

' ""E O t NPATENTS 

